Magnet wire



0. F. FREELAND MAGNET WIRE Filed Dec. 7, 1937- couaqraa I INVENTOR O F D BY ATTORNEY can 00:70?

ENAMEL REINFORCING STRAND of 61853 fill/"EH73 0 mm W E 1 m I 2 3 mm m m m m F F F :0 R H a K A A A u n r m :9 L, fi A Z M a N n ma 15 between two and three Patented June 20, 1939 TPIA'TENT orrics 2463.119 MAGNET WIRE Orville F. Freeland, North Muskegon, Mich, as-

signor to Anaconda Wire 8t Cable New York, N. Y.,

Company,

a corporation of Delaware Application December 7, 1937, Serial No. 178,516

5 Claims. 1v4 124) This invention relates to electric conductors of the smaller sizes and more particularly to conductors which are'used in winding coils, solenoids or other electrical apparatus. The wire used in secondary windings of transformers and similar apparatus is necessarily of extremely small diameter, so that the completed coil will not be excessively expensive or bulky. It is possible to use conductors of small diameter since the current is almost infinitesimal, while the potential may be extremely high: at the present time magnet wire is commercially manufactured in sizes as small as #42 Awg. which has a nominal diameter of 0.0025", Such a wire has-an ultimate strength ounces.

' While conductors of this order of fineness are not required to carry tensile stress while in service, a certain amount-of tension is unavoidable during the manufacturing processes. Since a secondary for a moderate sized transformer may 1 contain many thousand turns of wire, the windings must be applied at high speed if production is tobe economical. Furthermore, the windings must be firm and holdtheir position within the coil as mechanical abrasion may destroy the in sulation' if the wire is loose and free toshift. .-:-Because'of the high speed and the tension necessary to produce a satisfactory assembly, the finer sizes of conductor may be over-stressed and 3 broken during windingp Ifthis occurs the coil i must either be rejected or tediouslyrepaired by brazing the broken .wire and re-insulating. it. The loss causedby ciallyhigh when single machine at the same time, since production on-all coils must be stop Having the foregoing in mind the present invention relates to a'magnet wire which'is re in'forced with a high-strength non-conducting strand. Other features of the inventioniwfll be described in connection with the accompanying.

drawing in which: I

Figure 1 is a perspective view, greatly enstructed in accordance with ,tion. he covering sheath removed.

the present inven- Fiimre '1, illustrating the relation ofthe contion of magnet 5s Referring to Figure 1, the metallic wire ll,

delays ofthis natureis ease: many coils are'wound in"a arged, of a small section of magnet wire conbeing progressively Figure 2 is a cross-section taken in plane AA of' indicatedinI'igui-eLa preferably formed of copper, may be coated in" accordance with present practice with a layer of enamel [3 which possesses high-dielectric strength and resistance to abrasion and bending. For purposes of explanation this conductor may 5 be considered to be of a size commonly used in secondary windings, for example #37 Awg. The diameter of this wire is 0.0045" and its area is 20 circular mils or 0.0000157 square inch. Assuming that the strength of the copper is 36,000 pounds 10 per square inch, which is the maximum value for soft wire, the ultimate strength of the wire would be 0.57 pound. A conductor of such low strength may of course be easily broken between the fingers and must be handled with extreme 1'5 care in manufacture. -To reinforce thenopper I have found that a strand of glass thread ii, composed of a multiplicity of twisted filaments may be laid parallel to the conductor H and secured in place by furnished for the wire. Glass yarns and threads are available at the present time which develop a strength approximately five times that of soft copper and the inclusion of a thread of this nature, whose diameter maybe considerably less than that of the conductor, will supplement the strength of the cop- .per to such a degree that the completed wire will withstand approximately four times the stress which may be carried by the metal alone. Furthermore. the cross-sectional shapeof the supplementary thread is readily deformed so that it assumes a crescent shape when bound to the conductor by an outer jacket; because of this, the

external diameter of the wireis increased but 5 slightly and a negligible amount of void area is -introduced beneath the outer coating. As compared to 's'31.-itil7 Awg. wire which is not reinforced, my improved conductorhas a cross-sectional area whichis only. fifty percent greater while the" strength has been increased three hundredfZ-- (300%) percent. e electrical characteristics .of the wire of course remain unchanged. A feature of this construction which is of special importance from the standpoint of corrosion lies in the fact that the reinforcing filament is;

non metallic in nature and therefore there tendency to accelerate failure as would case if a dissimilar metal outer jacket of the wire is is no" be the,- was employedr The comparatively uniminvention is concerned, sinceit servesmerely to hold the reinforcing strands in position adjacent the conductor. As

serving I! of silk or cottonthreadsma'ybeusedorasindicatedforthis whatever outer jacket is.

purpose. In Figure 3, a layer IQ of enamel, lacquery or resin, applied either from a solution or extruded about the wire, will be equally satisfactory.

While I prefer to use glass threads as a reinforcing medium, since this material possesses high-strength and resistance to heat and absorption of moisture, there may be situations where a fibrous strand of other composition would be satisfactory for this purpose.

What I claim is:

1. An electric conductor comprising a metallic wire and a non-metallic reinforcing strand laid parallel to said metallic wire, the tensile strength of said reinforcing strand being at least equal to that of said metallic wire, said reinforcing strand being located adjacent the outer surface of said metallic wire and bound to said wire by an outer non-metallic jacket.

2. An electric conductor comprising a metallic wire and a non-metallic reinforcing strand laid parallel to said metallic wire, said reinforcing 'strand being located wholly externally of said metallic wire, the strength of said reinforcing strand being at leastequal to that of said metallic wire.

3. An electric conductor comprising a metallic wire and a reinforcing strand composed of glass filaments laid parallel to said metallic wire, said reinforcing strand only partially enclosing said wire and bound to said wire by an external fibrous jacket.

4. An electric conductor comprising a metallic wire and a reinforcing strand composed of glass filaments laid parallel to said metallic wire, the

.' tensile strength of said reinforcing strand being at least equal to that of said metallic wire, said reinforcing strand being bound to said metallic wire by an outer jacket and deformed to partially conform to the surface of said metallic wire.

5. An electric conductor comprising a metallic wire and a reinforcing strand of glass filaments laid parallel to said metallic wire, said reinforcing strand being located wholly externally of said metallic wire and having a tensile strength at least 

